<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        /* 1.给收到float 影响的元素 clear:both;
           2.给父元素加overflow:hidden */
    .parent{
        width:200px;
        height:100px;
        background:red;
        overflow:hidden
    }
    .two{
        width:100px;
        height:100px;
        background:blue;
        float:left;

    }
    .three{
        width:300px;
        height:300px;
        background: rgb(121, 35, 106);
        /* clear:both; */
        
    }
    </style>
</head>
<body>
    <div class="parent">
        <div class="two"></div>
    </div>
    <div class="three"></div>
</body>
</html>